Newbie help - editing theme

I downloaded the muscispace theme and need to change the color of the site (purple and pink do not work for a country music band lol) but I cannot find the option to edit the style.css, am I not allowed to do that with this theme?
On the blogs i see I am supposed to find a button under apearance that says theme editor but I cannot find this option...
I am a complete newbie to wordpress so any help is greatly apreciated

Hi!
It comes with an experience. You can edit style.css on page Appearance --> Editor in the dashboard of your website.